Brush oscillating assembly



Oct. 23, 1962 B. L. MIMS ETAL 3,060,397

BRUSH OSCILLATING ASSEMBLY Filed May 28, 1959 lo I 4.5 .1. 84 13 INVENTORS BRUCE L. M/MS HENRY KONET BY L g g M QTTOPNEY 3,050,397 Patented Oct. 23, 1962 free 3,060,397 BRUSH OSCILLATING ASSEMBLY Bruce L. Mims, Danbury, Conn., and Henry Konet, Hohokus, N.J., assignors to The Barden Corporation, Danbury, Conn, a corporation of Connecticut Filed May 28, 1959, Ser. No. 816,605 2 Claims. (Cl. 339) Our invention relates to a brush oscillating assembly and more particularly to a compact brush and slip ring unit which overcomes the effect of coulomb friction.

The resistance which must be overcome in producing relative motion between a pair of contacting members includes a static or coulomb friction component and a viscous friction component. Coulomb friction is resistance to motion other than that resistance resulting from viscous friction effects owing to Windage, lubricant drag, and the like. In relatively low speed and low friction installations such, for example, as in a slip ring and brush pick-off assembly of a precision gyroscope, coulomb friction plays an important part in determining the shaft torque which must be applied to cause motion between the slip rings on the shaft and the brushes carried by the gyroscope gimbal or the like. In such installations coulomb friction may seriously affect the operating characteristics of the gyroscope. In modern gyroscope assemblies such as are used, for example, in missile control systems and the like, size and weight of the components are of paramount importance.

We have invented an oscillating brush assembly which overcomes the effect of coulomb friction. Our assembly is a light and compact unit. It is simple in construction and relatively easy to manufacture.

One object of our invention is to provide an oscillating brush assembly which minimizes the effect of coulomb friction in a precision gyroscope pick-off assembly or the like.

Another object of our invention is to provide an oscillating brush assembly which is a light and compact unit.

A further object of our invention is to provide an oscillating brush assembly which is simple in construction and which is relatively easy to manufacture.

Other and further objects of our invention will appear from the following description.

In general our invention contemplates the provision of a slip ring and a brush mounted for independent rotary movement on a support in positions at which the brush engages the slip ring. We provide our assembly with means for continuously oscillating the slip ring and brush with respect to each other to minimize the effect of conlomb friction on the assembly.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGURE 1 is a sectional view of our oscillating brush assembly.

FIGURE 2 is a end view of our oscillating brush assembly removed from its support and taken along the line 22 of FIGURE 1.

FIGURE 3 is a sectional view of the oscillating means of our oscillating brush assembly removed from its support, taken along the line 33 of FIGURE 1 and drawn on a reduced scale.

Referring now more particularly to the drawings, our assembly, indicated generally by the reference character 16 includes a support 14 which may, for example, be a gyroscope gimbal ring which carries the gyroscope rotor housing 12. We provide respective bearings, indicated generally by the reference characters 16 and 18, for rotatably supporting the shaft 29 of housing 12 in an independently rotatable brush support 22. We secure the re spective inner rings 40 and 42 of the bearings 16 and 18 to shaft 20 for rotation therewith. We dispose the outer rings 44 and 46 within a recess 48 formed in the member 22. Respective retaining rings 50 and 52 retain balls 56 and 58 between the inner and outer rings of the bearings 16 and 18.

We employ respective bearings, indicated generally by the reference characters 69 and 62, for rotatably supporting the member 22 within a housing 64 carried by the gimbal 14. We employ any appropriate means known to the art for securing the respective inner rings 66 and 68 of bearings 60 and 62 to the member 22 for rotation therewith. We mount the outer rings 70 and 72 of bearings es and 62 on an annular boss '74 formed in the housing 64. Retaining rings 76 and '78 hold the balls 80 and 82 of bearings 60 and 62 in position between the inner and outer rings of bearings 69 and 62. We employ any convenient means such, for example, as screws 84 for securing an annular end plate 86 to the housing 64.

Our assembly includes a brush block 34 secured to an annular flange 88 on the member 22 by any suitable means such as screws 32. The block 34 carries a plurality of pairs of brushes 36. The brushes of each pair engage diametrically opposite points on a respective slip ring 99 on shaft 29. We separate adjacent slip rings 90 by means of insulating discs 38 carried by the shaft 24%. We provide the block 34- with a number of terminals 92 by means of which electrical connections can be made to the brushes 36 in a manner known to the .art. Electrical connections from the slip rings 90 to the electrical components within rotor housing 12 may be made in any appropriate manner known to the art through the hollow shaft 2i). We mount a spool 24 within the housing 64 for receiving a winding 94 adapted to be energized from a suitable source of alternating current (not shown) through conductors 96 and 98. We form the spool 24 from a magnetic material and provide the spool with a plurality of axially extending poles 109.

We mount an Alnico permanent magnet 28 provided with poles 39 on the member 22 for rotation therewith. Magnet 28 has alternate north and south poles 3i disposed adjacent the poles 190 formed on the spool 24. When the winding 94 is energized from a source of alternating current, during one half cycle the magnetic flux in spool 24- can be considered as emerging from the pole 100 and during the other half cycle the flux can be considered as entering the poles 169. During one half cycles of the alternating current supplied to winding 94, the south poles 30 tend to align themselves with the poles ltltl. During the other half cycle, the north poles 30 tend to align themselves with the poles 100. Owing to this action the member 22 and the brush block 34 carried thereby continuously oscillate around an axis on the support to overcome the coulomb friction between brushes 36 and slip rings 90. From the foregoing it will be appreciated that during one half cycle of the alternating current supplied to winding 94 fiux flows out of the poles so that these poles are north poles and during the other half cycle flux flows into the poles 100 with the result that they are south poles. When the poles 100 are north poles, the north poles 39 .are repelled by the north poles 100 and the south poles 30 are attracted by the north poles 109. Consequently, member 22 is urged to move in one direction around its axis of support during this half cycle. On the next or reverse half cycle, member 22 is urged to rotate in the opposite direction. The end result of these forces tending alternately to rotate member 22 first in one direction and then in other direction on alternate half cycles of the supply is an oscillatory movement of member 22 with respect to the support 14.

In operation of our oscillating brush assembly, winding 94 is energized with the result that the member 22 and the brush block 34 continuously oscillate. Thus coulomb friction need not be overcome in order to produce relative rotation between the housing 12 and the gimbal 14.

It will be seen that We have accomplished the objects of our invention. We have provided an oscillating brush assembly which overcomes the effect of coulomb friction. Our assembly is light and compact. It is simple in construction and relatively easy to manufacture.

It will be understood that certain features and subcombinations are of utility and may be employed Without reference to other features and subcombinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is, therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, what we claim is:

l. A slip ring and brush unit including in combination a housing, a member, means mounting said member for rotary movement around an axis on said housing, a shaft, means mounting said shaft for rotary movement on said member around said axis, a pair of contacting electrically conductive elements, means mounting one of said elements on said shaft for movement therewith, means mounting the other one of said elements on said member for movement therewith, electromagnetic means adapted to be energized with alternating current continuously to oscillate said member around said axis and means mounting said electromagnetic means within said housing.

2. A slip ring and brush unit including in combination a housing, a member, means mounting said member for rotary movement on said housing around an axis, a shaft, means mounting said shaft for rotary movement on said member around said axis, a pair of electrical contacts, means mounting one of said contacts on said member for rotation therewith, means mounting the other of said c0ntacts on said shaft for rotation therewith, electromagnetic means adapted to be energized with alternating current continuously to oscillate said member around said axis, said electromagnetic means comprising a stator and a rotor, means mounting said stator within and on said housing and means mounting the rotor within said housing on said member.

References Cited in the file of this patent UNITED STATES PATENTS 1,067,864 Christians July 22, 1913 1,128,270 lnrig Feb. 9, 1915 1,921,983 Wittkuns Aug. 8, 1933 1,990,767 Whittsitt et al. Feb. 12, 1935 2,037,457 Colson Apr. 14, 1936 2,446,673 Sprague Aug. 10, 1948 2,451,872 Rogers Oct. 19, 1948 2,774,831 Lafferty et a1. Dec. 18, 1956 2,874,362 Blanding Feb. 17, 1959 FOREIGN PATENTS 317,313 Germany Dec. 17, 1919 

